Sony Ericsson will be the first global client, and the ten-strong agency will be responsible for developing integrated campaigns throughout Latin America.
Stewart Shanley, the joint chief executive of Iris, will oversee the office with Alex Rodrigues, the global client services director.
The day-to-day running of the office will be jointly managed by Patricio Sanchez, previously of the C-Com Group, and Sandra Cuesta, who joins from Leo Burnett.
It is Iris' eighth global office and follows the opening of bases in Delhi, Singapore and Los Angeles last year. More are planned for later this year.